1. Technical Field
The present invention relates to elevators and, more particularly, to a telescoping door system for an elevator.
2. Background Information
Elevator systems typically include a car which can be drawn to any one of a plurality of landings within a hoistway to accommodate passengers. The car and each landing includes a doorway defined by at least one vertically extending jamb and a threshold extending across the bottom of the opening. For safety purposes, both the car and each of the hoistway landings comprise a door system to prevent access to the elevator car until the car is safely positioned at a particular landing.
Telescoping door systems, also known as two speed door systems, are a popular door system that can be arranged in a side opening configuration or a center opening configuration. In the side opening configuration, a fast door and a slow door are provided that extend across the doorway threshold in the door closed position or slide into a door pocket on one side of the doorway in the door open position. The stroke and the speed of the fast and slow doors are coordinated such that the fast door travels a greater distance than the slower door in approximately the same amount of time; hence the descriptive name "telescoping" or "two speed". The center opening configuration operates similarly except that there are two pairs of "side" opening doors included, one on each side of the opening. Each pair of doors extends across the doorway threshold and in contact with the other set of doors in the door closed position, or slides into a door pocket on the respective side of the doorway in the door open position.
The fast door may be more specifically described as comprising a fast car door panel and a fast hoistway door panel. The slow door comprises a slow car door panel and a slow hoistway door panel. When a car is properly positioned at a landing, the fast cab door panel and the fast hoistway door panel are positioned adjacent each other and the slow cab and hoistway panels are positioned outside of the fast door panels; i.e., on the opposite sides of the respective fast panels. In the door open position, the fast and slow panels are tucked into the door pocket parallel one another, with the fast panels positioned between the slow panels. The edge of the door panel on the jamb side of the doorway is defined as the leading edge and the edge of the door panels on the opposite, or "pocket side", of the doorway is defined as the terminal edge. When the doors are extended across the doorway threshold (i.e., the closed position), the leading edge of the fast door is either in contact with the jamb (the side opening configuration) or in contact with the leading edge of the other fast door (the center opening configuration). In this position, the leading edge of the slow door(s) is in close proximity to the terminal edge of the fast door.
There are a number of ways known to drive telescoping doors. In one embodiment, the drive assembly includes an electromechanical drive, a coupler for coupling the fast car door panel to the fast hoistway door panel, a first linkage for connecting the fast and slow car door panels, and a second linkage for connecting the fast and slow hoistway door panels. The coupler comprises a roller and vane combination. The rollers are attached to the fast car door panel and a vane is attached to every fast hoistway door panel. Alternatively, the rollers may be attached to every fast hoistway door panel and the vane attached to the fast car door panel. When the car enters the landing, the rollers are received within the vane, thereby coupling the fast car door panel and the fast hoistway door panel.
The first linkage is a mechanical linkage connecting the fast car door panel and the slow car door panel. Typically, the first linkage is a pivotal linkage attached to the fast car door panel and the slow car door panel at different radial points; i.e., if the fast door is to have twice the speed and travel, it is attached to the pivoting member at a distance away from the pivot point of the pivoting member twice that of the linkage connecting the slow door. The electromechanical drive is attached to the pivoting member on the side of the pivot point opposite that attached to the doors. Alternatively, the fast and slow car door panels could be attached to each other with an air cord assembly; i.e., a cable and pulley assembly where the slow door is roped to the fast door such that the speeds of the two doors are a multiple of one another.
The second linkage is similar to the first linkage except that it is applied to the hoistway door panels. The first and second linkages described heretofore connect the slow and fast doors of the car and hoistway such that movement of one of the fast door panels will cause the connected slow door panel to move as well. Furthermore, driving the first linkage with the electromechanical drive will cause both the hoistway and car doors to actuate because of the Coupling connecting the fast car and hoistway door panels.
Closing and opening times for doors are a vital consideration in elevatoring for several reasons. A person of skill in the art will recognize that it is desirable to minimize the time necessary to open and close elevator doors. Minimizing elevator door actuation time increases the efficiency of the elevator as well as the perception of quality. Safety codes dictate, however, that the closing speed of an elevator door is limited by a maximum allowable kinetic energy developed by the moving door.
The kinetic energy of an elevator door can be determined by using the kinetic energy equation, K=1/2 mv.sup.2, where "m" represents the total mass of the door system being moved and "v" represents the velocity of the door system being moved; i.e. distance traveled per unit time. The mass of the door system is generally computed by totaling the masses of all the individual pieces rigidly attached to the door; e.g., if all four door panels are mechanically connected, then the mass of all four door panels is summed in determining the kinetic energy of the door system. The velocity of the door is generally determined by averaging the speed of the door over a predetermined distance within the full travel of the door. From the equation it can be seen that the mass of the door is directly related to the kinetic energy of the door and the time component of the velocity is exponentially, inversely related. Hence, increasing the mass of the door increases the kinetic energy of the moving door, assuming the velocity is constant. Increasing the velocity of the door also increases the kinetic energy because the time component of the increased velocity is exponentially, inversely related. It is, therefore, difficult with presently known door drive arrangements to improve the closing speed of an elevator door without increasing the kinetic energy of the door(s).